The Collaborative International Dictionary of English v.0.48:

dissociate \dis*so"ci*ate\ (d[i^]s*s[=o]"sh[i^]*[=a]t), v. t.
   [imp. & p. p. Dissociated; p. pr. & vb. n. Dissociating.]
   [L. dissociatus, p. p. of dissociare to dissociate; dis- +
   sociare to unite, associate, socius companion. See Social.]
   To separate from fellowship or union; to disunite; to
   disjoin; as, to dissociate the particles of a concrete
   substance.
   [1913 Webster]

         Before Wyclif's death in 1384, John of Gaunt had openly
         dissociated himself from the reformer.   --A. W. Ward.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

dissociated \dissociated\ adj.
   1. not connected or associated.

   Syn: unconnected.
        [WordNet 1.5 +PJC]

   2. (Chem.) diffusing independently in a fluid; -- said of
      ions or molecules which may form relatively stable
      associated structures; as, the products become rapidly
      dissociated from the active site of the enzyme. Opposite
      of associated.
      [PJC]